The estimated prevalence of obesity, hypertension, dyslipidemia, diabetes and smoking in young adulthood suggests a higher than anticipated risk of cardiovascular disease (CVD) in an age group often characterized as unburdened by chronic illness. Despite that suggestion, changes in and manifestations of CVD risk through the fourth decade of life have not been examined in a large, contemporary, or nationally representative study of young U.S. adults at the forefront of the obesity epidemic. Therefore, Program Project investigators propose to include collection of biological data and specimens in Wave V of the National Longitudinal Study of Adolescent Health (Add Health). The biological data will be important in identifying change in and onset of multiple chronic diseases. The focus of the proposed effort is collection of anthropometric, cardiovascular, metabolic, inflammatory, renal and pharmacoepidemiologic measures. These measures were selected based on scientific knowledge of the leading causes of chronic disease morbidity and mortality through age 40, the role of specific biological processes in their causation and consequences, as well as the ability of established measures to characterize these processes. The Biology Core will oversee the collection, assay, and archival requirements of biological specimens from the Add Health cohort. Core staff will clean, document, and interpret assay results and will work with the Dissemination Core to make these data available to the Program Project subprojects and to the larger research community. The Core has multiple objectives: (1) to identify, evaluate, and recommend innovative, appropriate and feasible biological measures; (2) to develop protocols for the collection of biological specimens and guide interviewer training in specimen collection; (3) to monitor the quality of specimens collected through interaction with field contractors and laboratories; (4) to monitor quality of data received from laboratories and oversee documentation of biological data; (5) to provide consultation and advice to Program Investigators as they integrate biological data in their subproject analyses; (6) to consult with external researchers on interpretation and use of Add Health biological data; and (7) to provide scientific leadership and oversight of Add Health research agendas incorporating biology in study design, objectives, and analysis by contributing to the development of research ideas and participating in a review process of proposed research using biological specimens and data. The Biology Core is led by two researchers who have extensive experience collecting biological specimens in large cohort studies. This Core will collaborate extensively with other cores and will provide data, collaboration, and consultation to the subprojects. Proposed activities of the Core will be useful in examining the ability of the U.S. to meet the aggressive goals of multiple prevention efforts, including a 20% improvement in the cardiovascular health of all Americans and a corresponding 20% reduction in CVD deaths by 2020. Such examination will generate actionable, timely knowledge for stakeholders at many levels.